1. Field of the Invention
The rotary dial pulse train analyzer described in the subject disclosure relates to telephone dial testing equipment generally, and more specifically, to the type of test equipment designed to test the operation of dials on a pass-fail basis. This test equipment can be used by the telephone operating companies in the testing of telephone sets to determine which sets may be returned to service without repair, or in testing telephone dials during the manufacturing process.
2. Description of the Prior Art
The prior art includes analog-type dial pulse testers such as the Boring U.S. Pat. No. 3,410,967, the La Barge et al. U.S. Pat. No. 3,243,526, and the Danville et al. U.S. Pat. No. 3,123,679 which measure the "percent break" ratio of a dial pulse train by the use of either relay counting circuits or RC timing circuits. These prior art pulse testing circuits require calibration or some other form of adjustment to provide and maintain accurate performance.
Other prior art patents, such as the Boatwright U.S. Pat. No. 3,735,263, and the Mann U.S. Pat. No. 3,603,745, show dial pulse testers which use various digital techniques to measure the percent break ratio of a dial pulse train. The percent break ratio of a dial pulse train is defined in the art as the ratio of the time during which the dial contacts are opened (i.e., "break") to the total duration of the dial pulse which is the sum of the interval that the dial contacts are closed (i.e., "make") and the interval that the dial contacts are open (i.e., break) i.e., total time = (make + break). The percent break ratio is used to describe the relative dimensions of a dial pulse; moreover, if it falls outside of a given nominal range, it may indicate a defective dial. The above prior art testers either measure the percent break ratio on an average basis, or use some form of dividing circuitry to obtain the result as a percentage figure.